Conductivity and Time–Temperature Correspondence in Polar Viscoelastic Liquids

Abstract

This work is focused on the conductivity study of viscoelastic liquids, taking as a model poly(2,3-dimethoxybenzyl methacrylate). Each isotherm, displaying the conductivity in the frequency domain, shows a plateau in the low frequency region, representing the dc conductivity. The covered frequency range by the plateau increases with the temperature. The frequency corresponding to the end of the plateau, ω c , marks the onset of the ac conductivity, which correspond in increasing order of frequency to Maxwell− Wagner−Sillars, glass−rubber transition and secondary relaxations. The contributions of the relaxation processes to the ac conductivity in the wholly frequencies range were analyzed. The time−temperature correspondence principle holds for the reduced ac conductivity. However, this principle does not hold for the components of the complex dielectric permittivity due, among other things, to the different temperature dependences of each dipolar relaxation processes. Analogueies and differences between the conductivity behavior of viscoelastic liquids and disordered inorganic solids are discussed.

50th Anniversary Perspective: Challenges in the Dynamics and Kinetics of Glass-Forming Polymers

“…Similar to the issue of different temperature dependences between the viscosity and segmental relaxations (though not for the same reasons), the dielectric and viscoelastic temperature dependences are not identical although they both show super-Arrhenius behavior. Such differences between the dielectric and viscoelastic responses in both the temperature dependences of the relaxation times and the strength of the various relaxations are not unusual for either polymers or small molecular glass-formers − and may arise (but not always) in part from the coupling of the dipole motions to the viscoelastic medium. , …”

Electrical conductivity properties of expanded graphite-polycarbonatediol polyurethane composites

“…Their electrical response is mainly associated with relaxation phenomena occurring under the influence of the alternating current (ac). The ac electrical response of disordered systems to electric perturbations results in the superposition of different contributions . These contributions are related to (i) the hopping process of localized charge carriers, (ii) the response produced by the molecular structure deformation, following on the diffusion of charges through percolation paths, and (iii) the dispersive response of the bound charges (dipolar response).…”

Pendant Chain Effect on the Synthesis, Characterization, and Structure–Property Relations of Poly(di-n-alkyl itaconate-co-isoprene) Biobased Elastomers

“…Each spectrum in Figure b shows a single broad relaxation peak, which shifts to higher frequencies with increasing side chain length, revealing the decrease in relaxation time. This relaxation is related to the glass transition and labeled as α-relaxation . The different profile of the spectrum of PDMII is probably attributed to the overlap of the dielectric α-relaxation and the strong conductivity contribution.…”

“…This relaxation is related to the glass transition and labeled as α-relaxation. 41 The different profile of the spectrum of PDMII is probably attributed to the overlap of the dielectric α-relaxation and the strong conductivity contribution. The different profile of the spectrum of PDNII and PDDII attributed to PDNII and PDDII mainly composed of isoprene unites.…”